linux-kernel - Re: return negative number for unsigned long function in kernel

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <45EE09B4.40207@zytor.com>
Date:	Tue, 06 Mar 2007 16:39:16 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	"Chen, Dongliang" <Chen.D@...-t.com>
CC:	linux-kernel@...r.kernel.org
Subject: Re: return negative number for unsigned long function in kernel

Chen, Dongliang wrote:
> There are lots of functions in the Linux kernel that are declared as
> unsigned long, but the return value is negative integer while error
> occurred. An example of these functions is do_mmap_pgoff in mm/mmap.c,
> which is defined as:
> 
> unsigned long do_mmap_pgoff(....)
> 
> In this function, it returns -ENODEV, -EPERM, -ENOMEM, -EINVAL, -EAGAIN,
> -EACCESS depends on the error type. My question is how should the caller
> perform error check based on the return value? 
> 

If you want to test for errorness, you could use the macro 
IS_ERR_VALUE().  Unfortunately the macro isn't all that safe, in that it 
will give you the wrong answer if it's ever used on something that 
*isn't* an unsigned long.

	-hpa

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/